#include <iostream>
#include <iomanip>
#include <cmath>
using namespace std;
int main()
{
   int N; 
   cin>>N;
   int a[10000];
    int aLen = 0;
   for(int i = 0; i<N; i++)
   {
       cin >> a[aLen];
       aLen++;
   }
    double ave = 0;
    for(int i = 0; i< aLen; i++)
        ave = ave + a[i];
    ave = ave / aLen;
    double sum = 0;
    for(int i = 0; i< aLen; i++)
        sum = sum + (a[i] -ave) * (a[i] - ave);
    cout << fixed << setprecision(5) << pow(sum/aLen,0.5);
}